Stimulants are a class of psychoactive drugs that increase central nervous system (CNS) activity, leading to higher energy, alertness, focus, and heart rate. These substances work by boosting key brain chemicals such as dopamine and norepinephrine, which enhance wakefulness and mental performance.

Common stimulant drugs include caffeine, cocaine, and amphetamines. While some stimulants are legally prescribed for conditions like ADHD and narcolepsy, misuse can lead to dependence, anxiety, insomnia, and cardiovascular problems.

Stimulants are widely recognized for their fast-acting effects on energy and concentration, but they also carry significant health risks when abused.